Incandescence
by PennyOfTheWild
Summary: [In some ways, he isn't older than him in the slightest.] Tobirama, Hiruzen, and the things Hiruzen learned from his sensei without Tobirama realizing it. AU, Kinship-verse, Hiruzen narrates.


**A/N:** Set in my AU where Izuna gives up his eyes, survives, and dies much later: all because I'm a sucker for bromance. I'm so sorry guys. This one's for equestrian-equine on tumblr! Also: the original fic was written in second person; I've modified it in accordance with FFNet's guidelines. If you'd like to read the original, head over to my tumblr (you can find the link on my profile).

A reminder: I appreciate faves, I really do: but feedback! A little goes a long way.

* * *

**Incandescence**

**Character(s):** Tobirama, Hiruzen, Izuna

**Pairings**: none

**Word Count:** 4,000

**Warnings:** Language

**Dedication**: equestrian-equine

* * *

Hiruzen finds his teacher much as he usually does: in the little room off the Hokage's office, close enough to hear if his brother calls, sitting amidst a stack of books and scrolls. Hiruzen smiles – he is so engrossed in whatever he is scribbling he does not notice when Hiruzen comes in – not even when he stands right behind him and leans over his shoulder.

"Tobirama-sensei," Hiruzen calls. He starts and looks up. Hiruzen sees his eyes focus; a wry smile appears on his face.

"Hiruzen," he says, "this eager to work on your day off?"

"You're one to talk, sensei," Hiruzen tells him, grinning, "and besides: how could I have slept in after what you told me?"

"Ah, it's my fault, I see," Tobirama-sensei says dryly, but he is still smiling. He puts down his brush and rolls his shoulders; it is a little after sunrise but Hiruzen is sure he has been up for hours already. He stands up, lifting his forehead protector from where it has been lying, discarded, on the ground, "alright, Hiruzen – time to go, then."

Hiruzen hurries past him to hold the door open; Tobirama-sensei shakes his head and Hiruzen grins.

"Where are we going, then?" he asks, because he's always loved asking questions even if the person he's asking doesn't love answering them.

"Ask me no questions and I'll tell you no lies," his teacher says absently, securing his forehead protector.

"Sensei," Hiruzen grouches, out of habit, because the answer was expected, and Tobirama-sensei ruffles his hair.

"Don't make such awful faces, Saru-chan," he teases, "your face will get stuck like that and Kami knows you need all the help you can get."

"You're so encouraging, sensei," Hiruzen tells him, and immediately endeavors to trip him; Tobirama-sensei dodges.

"Next time, Hiruzen," he says.

Hiruzen laughs and follows him down the corridor.

* * *

Hiruzen is quiet till Tobirama-sensei takes him past their usual training field – and he holds his silence for several moments after _that_, too – but then Tobirama-sensei takes a side road into the village and Hiruzen's curiosity gets the better of him.

"Tobirama-sensei – where are we going?"

Tobirama-sensei looks back at Hiruzen, the corners of his eyes crinkling. "We're going to see a friend of mine," he says.

"Sensei – you _have _friends?" Hiruzen says cheekily, and Tobirama-sensei raises an eyebrow.

"Hilarious," he intones.

"But honestly, sensei," Hiruzen says, "I thought you were going to teach me some killer new technique."

"_You _said that, not me," Tobirama-sensei reminds him, and holds up a hand when Hiruzen opens his mouth to protest, "Hiruzen – what elemental affinity do the shinobi of the Sarutobi clan possess?"

Hiruzen rolls his eyes. "Earth or fire, sometimes both, like I do," he says, "and you asked me that yesterday."

"Well," Tobirama-sensei says, "seeing as I can't teach you _Katon_ jutsu, this friend of mine we're going to see is going to teach you instead."

Hiruzen considers this for a moment. "Sensei," he tells his teacher, "didn't it cross your mind that I could learn _Katon _from _somebody in my family_?"

"Insolent little brat, aren't you?" Tobirama-sensei's voice is all affection, "remind me why I put up with you, Hiruzen."

"I'm not sure – I think it may be because of my innate charm, sensei."

He laughs out loud – and Hiruzen revels in his ephemeral success (before the next round begins, because this is a game he often plays, and it is a never-ending one).

"This friend of mine's abilities are a little special," Tobirama-sensei says, "I'm sure you'll find him interesting."

By this point they have left Leaf's businesses and stores behind and are entering the residential areas. It is too early in the morning for any real activity, but there are several people – mostly shinobi – striding purposefully to wherever it is they are headed towards, walking the walk of soldiers, long decisive steps and restless eyes even though it is peacetime.

Hiruzen is a soldier and the son of a soldier and the disciple of one: but there is nothing that saddens him more than war (and later, when he is older, he will do his best to prevent it – needless fighting and wanton violence and senseless killing – but he will fail like the ones before him failed although they and he hoped he would succeed).

It is late in the year: winter is almost upon Fire Country, and the wind whistling between the quiet sleeping houses nips at Hiruzen's fingers and reddens his ears and he looks enviously at his teacher, who is blithely unaffected by it.

Tobirama-sensei turns into yet another street: this one is wide and lined with trees, mottled colorful leaves piled up on the pavement: ahead of them, the gates to a compound loom; squinting his eyes, Hiruzen can make out a bicolored fan – freshly painted, by the looks of it – gleaming proudly on the doors.

"Keep up, Hiruzen," Tobirama-sensei calls, and Hiruzen realizes, with a start, that he has been standing, staggered, in the middle of the road and Tobirama-sensei is several yards ahead– and Hiruzen runs to catch up.

There is a shinobi at the gate, twiddling a kunai between his fingers, a dark shock of hair obscuring his eyes. He looks up as Hiruzen and Tobirama-sensei approach.

"Senju-san," he greets Hiruzen's teacher, "this is quite suspicious: what brings you out here this early in the morning?"

"I intend to murder your clansmen in cold blood," Tobirama-sensei informs him sardonically, "which is why I am coming in through the main gate."

To Hiruzen's surprise, the guard smiles, his mouth relaxing into an easy curve. "Maybe I ought to have tried something different this time, hmm?"

"Whatever works for you, Sanshi," Tobirama-sensei says, "how is he? Is he home?"

Sanshi Uchiha shrugs. "You probably know better than I do how he is – but yes, he's home. Go on in." He turns in Hiruzen's direction. "Ah," he says, "you're Hiruzen Sarutobi, aren't you? What, are you collecting info for your clan, boy?"

"Really, Sanshi," Tobirama-sensei chides, "is that what you're doing nowadays? Aggravating children?"

Sanshi-san laughs and ruffles Hiruzen's hair, "I hope you don't turn out as uptight as this teacher of yours," he tells Hiruzen, "life is too short to waste every moment being so serious." He pushes the gates open. "Off with you now," he says, "and make sure you don't bump into the esteemed leader; he is in an awful mood today."

The compound, in stark contrast to the stillness outside, is almost bustling; there are several strange looks (and a few smiles) directed at them way as Hiruzen follows Tobirama-sensei down the road. The compound, Hiruzen discovers, is built similarly to the Senju and Sarutobi compounds – the same wide street winding between the same wooden houses (all erected using the Mokuton) – but there is a fan on every door and the colors, too, are different – blue and black and red.

Tobirama-sensei leads Hiruzen past the houses; there is an expanse of grass leading up to a cluster of giant, closely-packed trees – and at the base there is a solitary house nestled in a little clearing, branches grazing the sloped roof. The door, Hiruzen notices as they draw nearer, is slightly ajar, the shoji panels slid away from the frame; Tobirama-sensei slips his sandals off at the doormat and you do the same; he sets a hand on the edge, noiselessly pushing the door further open; Hiruzen steps over the threshold after him.

The hall is dark, and narrow; as Hiruzen's eyes adjust he notices there are only three rooms in the house – a kitchen, a bedroom towards the back, and a sitting room – and apart from Hiruzen and his sensei, there seems to be no-one there – and the atmosphere is closed, and stifling, as if there's something heavy in the air that is pressing against Hiruzen's chest.

If Hiruzen didn't know better he'd say it was chakra.

There is a rustle at the end of the hall; the shoji panels closing off the room Hiruzen presumed to be the bedroom creak open and a figure appears, silhouetted against the light filtering in from inside the chamber – a young man, dark-haired and slight, clothed in a loose white yukata belted with a black obi. He raises his head; there is a band of cloth tied tight around his eyes and with a jolt Hiruzen realizes he must be blind – and the heavy oppressiveness bearing down on in the corridor is coming from him and with a little thrill Hiruzen realizes that it _is _chakra.

"You're so obnoxious, Tobirama," his voice is a low rasp, "could you be any louder? I could feel your chakra signature all the way up the road."

Hiruzen notes to himself that this is a classic example of the pot calling the kettle black.

"Anyone would think you're overjoyed I'm here," Hiruzen's teacher notes, "your sensing is getting better."

The other man scowls as he approaches. "Don't patronize me," he mutters, and then he turns his head in Hiruzen's direction – and the sense of unease increases tenfold.

"Who's the brat? He feels like a Sarutobi."

"He is a Sarutobi," Tobirama-sensei says easily, setting a hand on Hiruzen's shoulder, "I brought him to see you. Hiruzen, this is Izuna Uchiha."

A slight flicker of – is it recognition -? flits across Izuna-san's face, "You've always been a bad liar," he says, and pulls the door to the sitting room open, "what ulterior motive brings you here? And don't say you felt I needed company because that's bullshit." He waves an indolent hand towards the room; Tobirama-sensei beckons Hiruzen inside.

"Calm down," Tobirama-sensei tells him; and Hiruzen quickly schools his expression into a more neutral one. "He doesn't bite."

"His chakra is suffocating,"Hiruzen whispers.

"You should've felt it when I still had eyes," Izuna-san says from behind him, and Hiruzen turns his head so fast he puts a crick in his neck. He chokes back a gasp, but cannot keep his eyes from watering. Izuna-san crosses over to the _zabuton_, throwing himself onto the cushion with a fluid, careless gesture that still manages to look graceful.

He taps his finger against his eye-covering. "Tobirama," he says, "if you expect me to teach this kid _Katon_, the answer is no."

"Perceptive as always, Izuna, but I'm not giving up that easily," Tobirama-sensei says, "and reign in your chakra: you'll suffocate Hiruzen."

"If he can't hold up against a little pressure," Izuna-san says loftily, lifting his nose into the air, "it's a waste of space to have him in my house in the first place."

"Firstly," Tobirama-sensei says, "this isn't a house – it's a shack – and remember: he's eight years old, Izuna."

Izuna-san turns towards Hiruzen again, his eyebrows lifting over his bindings, "Eight? Has it really been - you aren't serious – his chakra signature is much too strong for that."

There's a look of faint pride on Tobirama-sensei's face and Hiruzen's heart expands. "Oh, I'm serious, alright," Hiruzen's teacher says, "why don't you take this out back?"

A little smile appears on Izuna-san's face; he cracks his knuckles, the smile growing into a full-blown smirk. "Ah," he says, "now I _am_ curious. But you'd better hope that hospital you're having built's got staff, Tobirama, because he's going to need it."

Hiruzen gulps.

* * *

Hiruzen is lying on his back in the middle of the clearing, his clothes singed beyond recognition, ash and soot darkening hishair and smudging his face. His chest rises and falls rapidly; his throat is blazing.

Tobirama-sensei is sitting on a boulder to Hiruzen's right, arms crossed, his heel set across the opposite knee.

For a blind man, Izuna-san (Izuna-sensei?) is fast (actually, he's faster than most seeing people) and Hiruzen is pretty sure the waves of chakra rolling off him are flammable.

"Again," Izuna-san tells Hiruzen from where he is standing, feet shoulder width apart, the skin around his eye-sockets creased around the glass eyeballs implanted in them, "or is that all you've got, _Hiruzen-chan_?"

Hiruzen struggles to his hands and knees.

"Of course not," Hiruzen rasps through his charred throat, "don't you know who you're dealing with?"

Out of the corner of his eye he sees Tobirama-sensei's face crease into a smile.

"A child," Izuna-san's voice is flat, bored. They have been at this for the better part of two hours, and apart from the quickness of his breathing he has nothing to show for it, "is who I'm putting up with."

Hiruzen coughs, winces, and resists the urge to curl up and die. The _Gokakyu_ eats up his chakra like no other jutsu he's been taught so far – and unlike the _Haisekisho_, where you transform chakra outside your body, the Fireball requires you to concentrate and convert chakra within your stomach – and the flames, licking and curling their way up Hiruzen's esophagus, are _hot_. He finds he has got newfound respect for the Uchiha, who submit themselves to this kind of self-inflicted pain on a regular basis.

Pushing himself to his feet, keeping his knees slightly bent, Hiruzen weaves the necessary hand signs - _horse, snake, tiger, monkey, boar, horse, tiger_ – and focuses his chakra. Izuna-san dodges Hiruzen's fireball just like he's dodged the others – ducking, weaving – "Increase your range," he shouts, "or you'll never get me!" and Hiruzen grits his teeth in frustration and just barely leaps aside to avoid his counterattack (his hand seals are so _fast_) the flames searing past his ear; behind him, a tree (poor, innocent bystander) bursts into flame.

Tobirama-sensei puts the fire out before it can spread – and Hiruzen decides that if he doesn't do something, and fast, between the two of them, he and Izuna-san are probably going to burn the forest down.

It takes too much time, Hiruzen thinks, to mold chakra long enough to form a perfect fireball – he is better than he was earlier this morning, of course, but Izuna-san's too fast – and if Hiruzen keeps playing by his rules they are going to be out here a long, long while.

Hiruzen's hands flit through the hand signs – but this time, instead of focusing his chakra into a sphere he forms a stream – a jet of fire that erupts from his mouth, arcing widely across the clearing. Izuna-san's face contorts, his eyebrows furrowing, the skin around his false eyes puckering; obviously, he is picking up the difference in Hiruzen's chakra signature – this time, his sidestep is slightly off-balance, a sheen of sweat beading over his forehead, his breath coming in uneven gasps. He is a single step away from slamming, back-first, into a tree.

"Hiruzen – " Tobirama-sensei starts, but Hiruzen has already begun forming the seals – a rush of adrenaline later, another blazing torrent leaps towards Izuna-san. His eyes widen and, for a moment, he disappears behind the blaze – and then, Hiruzen's improvised fireball is thrust towards him; Hiruzen can _feel_ the ripple and surge in Izuna-san's chakra and then _he _is the one being pushed back, Hiruzen's chakra reserves dwindling as he struggles to maintain the _Gokakyu_.

Izuna-san bears down on him, Hiruzen's fireball sputtering and petering out – instinctively, he squeezes his eyes shut against the heat-wave threatening to overwhelm him– and abruptly, it stops – and instead, there is a thud and the sound of a wet, hacking cough.

Hiruzen opens his eyes. Izuna-san is on his knees, his hands pressed to his mouth; there is blood seeping from his eyelids – his fingers, too, are red and damp.

"Tobirama-sensei!" Hiruzen shouts, turning in his direction – but he is already there, kneeling on the ground beside Izuna-san, probing fingers already cloaked in healing chakra.

"You are such an exhibitionist," he rebukes, and beneath the disapproval Hiruzen can hear a current of concern. Tobirama-sensei lowers Izuna-san's head to the ground; the Uchiha grimaces.

"Shut up," Izuna-san says, almost fondly, and Tobirama-sensei's eyes tighten.

"Hiruzen," he says, "please retrieve my first aid kit."

Hiruzen reaches into his teacher's back pocket with shaky fingers and pulls it out, setting it down and fumbling with the lid, lifting it open.

"I'm sorry," he says, "I didn't know – "

"It's not your fault," Izuna-san rasps. He turns his head in Hiruzen's direction, sightless eyes fixed eerily on Hiruzen's, blood caking his cheeks. "Modifying the _Gokakyu_ to better suit your chakra control like that," he says, "you're something else, Hiruzen."

Hiruzen bites his lip, heat rushing to his face. "Thank you," he whispers.

Izuna-san twists his head towards Tobirama-sensei. "You're awfully quiet," he says, a slight gurgle – is it laughter? – hanging off the edge of the last word.

"You're an idiot," Tobirama-sensei informs him crisply. "You obviously haven't been doing the exercise I told you to do – because the _tenketsu_ around your eye-sockets is still humming with chakra – and if your body keeps trying to redirect energy to – "

" – to the Sharingan I no longer have this is going to keep happening," Izuna-san cuts him off, "and if it continues I will no longer be eligible for an eye transplant in the future. I know. You've told me already."

"Clearly," Tobirama-sensei snaps, his eyes flashing, "you haven't been listening. I'm not a miracle worker, Izuna – there's a limit to what medical ninjutsu can do – "

"Has it never crossed your mind," Izuna-san says quietly, reaching up and tapping Tobirama-sensei's chin, "that maybe I don't want a transplant?"

"Has it never crossed your mind," Tobirama-sensei's voice is hard – but his fingers, wiping the dried red flecking his friend's face – are infinitely gentle, "that wallowing in self-pity is _not_ how you're supposed to deal with your problems?"

Hiruzen concentrates on handing Tobirama-sensei his equipment and tries to ignore the feeling thathe is intruding on something he ought not to be interfering with; if Tobirama-sensei wanted him to leave, Hiruzen tells himself, he'd send him away.

"I am not wallowing in self-pity, Tobirama Senju," Izuna-san says acerbically, "and even if I was, it's none of your business and it's definitely not your place." He drops his hand, his expression mulish. Tobirama-sensei chooses this moment to pop the glass eyes out of their sockets with a sickening squelch, his own eyes narrow and flinty. Izuna-san bites back a yell.

"You could have warned me!" he half-shouts, his mouth contorted into a scowl.

Now empty, his eye sockets are a vicious, inflamed red , the dark hollows extremely unsettling. Hiruzen fights the urge to flinch.

"I'm _sorry_," Tobirama-sensei says unapologetically, "I thought it was _not my place_," but Hiruzen notices he slides chakra into the swollen skin below Izuna-san's eyebrows and cheekbones – and then Tobirama-sensei looks at his student; Hiruzen hands him the gauze and lays out the surgical tape.

There are several moments of silence; Tobirama-sensei binds Izuna-san's ruined eyes mechanically, his face blank. The corners of Izuna-san's mouth are pulled down; there are lines around his nose and looking from him to his teacher Hiruzen notices (nearly) identical lines creasing Tobirama-sensei's face.

Hiruzen wonders if this is a side-effect of being a shinobi: living too hard, burning out too fast, and dying too young.

All the while, the flats of Tobirama-sensei's left index and middle fingers are fixed against Izuna-san's temple, a faint green glow enveloping the digits, Izuna-san's face relaxing under the continuous onslaught of healing chakra – his breathing, too, deepens and evens out.

"Tobi," he says hazily, "the truth is – there are some things you just can't fix. You can try – but there's always going to be a scar – something left behind – and I think it's better, for me – to be properly broken than to be _fixed _into something less than whole. What I've lost – it's honor, Tobi – I couldn't live with myself if I settled – "

"You wouldn't be settling for anything," Tobirama-sensei mutters, "you would be choosing to move past – "

"It would be a betrayal of myself," Izuna-san says with an air of finality, the last word carrying. Hiruzen imagines that, if he had had eyes, he would have closed them now: the faint smile that would have accompanied the gesture is already hovering at the edges of his mouth.

Tobirama-sensei lifts his hands away, flexing his fingers. He looks down at Izuna-san's face, his chin stubborn, and with a sudden flash of insight Hiruzen realizes the twenty-four-years his teacher has lived haven't, in fact, been very many years at all.

In some ways, he isn't older than Hiruzen in the slightest.

"I will never understand you Uchiha,"Tobirama-sensei says, and Hiruzen picks out frustration, and anger – and maybe a little bit of wistfulness, buried deep, in his voice.

"And that is where we differ, my friend," Izuna-san says so faintly Hiruzen nearly misses it – and then he falls silent, and a moment elapses before Hiruzen realizes he has fallen asleep.

Tobirama-sensei's shoulders slump. "Looks like your lesson got cut short, Hiruzen," he says, in a feeble attempt at humor.

"It was a good lesson," Hiruzen tells him, and is rewarded with a faint smile, and Tobirama-sensei runs a clinical eye over Hiruzen, healing cuts and burns with routine efficiency. He brushes the dirt out of Hiruzen's hair.

And then he sighs, and turns back to his friend, and Hiruzen watches as he attempts to wake Izuna-san up – two, three times – failing miserably. "I'll be right back," he tells Hiruzen, and gathers his friend up into his arms (it is an incongruous sight; they are nearly the same height, and similarly built – and Hiruzen decides that Izuna-san must be even lighter than he appears – or else, Tobirama-sensei is stronger); as he straightens, Izuna-san's head lolls against his shoulder, and Tobirama-sensei huffily blows dark hair out of his face.

* * *

He is back less than five minutes later, a contemplative twist to his eyebrows, his mouth fixed into a scowl. He exhales, and runs his fingers through his hair, his back to Hiruzen

"Let's go, Hiruzen," he says without turning around, and waits till Hiruzen comes to stand beside him; he follows his teacher closely, their shadows melting into one. The two of them walk in silence; Tobirama-sensei nods to the guard who relieved Sanshi-san sometime while they were in the compound, and then they are crossing the long road leading from the compound gates. Hiruzen sneaks a look up at him; he is looking straight ahead and does not seem to notice the scrutiny.

Hiruzen bites his lip and edges closer, slipping his (small) hand into his teacher's (much larger) one and pressing his face against Tobirama-sensei's sleeve.

His fingers close around Hiruzen's (Hiruzen's palm, still soft, slips over his callouses); Hiruzen's teacher looks down at him, raising a bemused eyebrow.

"Everything alright, Hiruzen?" he asks, and everything about it (his voice, rising on the last syllable of Hiruzen's name, the relaxed curve of his eyes) is so normal it is almost jarring; Hiruzen expected him to sound different, somehow – and he wonders if he read him wrong.

"I'm fine," Hiruzen tells his teacher, "are _you _okay, Tobirama-sensei?"

His eyes widen; he looks at Hiruzen for a moment, as if he has stunned him into silence, and then he laughs, and Hiruzen silently gives himself another point (although he's not sure he deserves it) – and then Tobirama-sensei ruffles Hiruzen's hair and swings him onto his shoulders; Hiruzen sets his chin on his teacher's head and pulls at _his _hair because he's a kid and that's what kids – even shinobi-in-training who are also geniuses – do.

"Oh, I'm okay, alright," Tobirama-sensei tilts his head back to look at Hiruzen, "but _you_ won't be after I tell your father about that potentially dangerous modification you made to the _Gokakyu_."

Hiruzen sighs. "Sensei," he says, "you're so unfair."

(And he is smiling so hard it hurts.)

* * *

_**Thank you for reading.**_


End file.
